Stimulation of the clonal growth and differentiation of feeder layer dependent mouse embryonal carcinoma cells by beta-mercaptoethanol.

Embryonal carcinoma cells are the undetermined stem cells of teratocarcinomas. Supplementation of culture medium with beta-mercaptoethanol permits the feeder layer independent clonal growth and differentiation of normally feeder layer dependent embryonal carcinoma cell lines. Differentiated cells within the clones appeared less than 6 days after plating and were distinguished from embryonal carcinoma cells by their morphology, lack of histochemically detectable alkaline phosphatase activity, and secretion of plasminogen activator. Over 70% of the colonies secreted plasminogen activator after 6 days. In comparison, a different embryonal carcinoma cell line which has lost the potential for substantial differentiation, either in vitro or in vivo forms very few clones (less than 1%) which secrete plasminogen activator. Embryonal carcinoma cells derived from the rare clones which secrete plasminogen activator have the same frequency of production of plasminogen activator secreting colonies as the parental cell line.